A melt reduction plant is operated in a two-stage process, wherein in a first step solid metal-containing raw materials are reduced by means of reduction gas and this pre-reduced material is smelted in a second step to produce liquid metal whilst simultaneously adding energy sources, in particular coal, coke, etc. Melt reduction plants in the context of this application are understood to include a blast furnace (operated using hot blast and/or oxygen), a plant using the COREX® or FINEX® process and further available melt reduction processes.
It is known that dry filters are utilized for cleaning, in particular hot, process gases, such as for example blast furnace gas from blast furnaces or top gas from reduction plants. It is advantageous in this situation that in contrast to wet scrubbing no sludges or wastewaters accumulate which in turn would need to be subjected to complex further treatment. It is furthermore known to clean the dry filters by backflushing with flushing gases, wherein the filter cake is released from the filter. Primarily compressed air but also nitrogen are used for this purpose in conventional techniques. The disadvantage in this situation is that additional process gases are required in considerable quantities.
It is known from JP 05-076803 A to arrange a filter in a cyclone separator, wherein following a coarse separation in the cyclone separator a fine separation takes place in the filter. The material separated in this case can be further processed.
WO 94/11283 likewise describes the separation of dusts from a conveying gas and the delivery of the dusts separated thereby to an open receptacle and the cleaning of the conveying gas in the cyclone separator and a bag filter.